1. Field of the Invention
The present invention relates to a frame structure for attaching a working implement to a vehicle having a main frame assembly including a plurality of frames spaced apart from one another transversely of the vehicle and extending longitudinally thereof.
2. Description of the Related Art
A frame structure of this type is disclosed in U.S. Pat. No. 4,087,009, for example. This known structure includes a pair of right and left vehicle frames extending longitudinally of the vehicle, and mounting bars extending parallel to the vehicle frames and connected thereto. The mounting bars carry brackets to which a backhoe implement is connected. A front loader implement is also attachable to the vehicle frames through vertical frames and support arms. In this connecting structure, a mounting range of the working implement transversely of the vehicle relies on the width of the vehicle frames. It is therefore necessary to ensure that the front loader implement, for example, does not interfere with front wheels, which allows only a limited freedom for the structure.
To avoid an interference between the front loader implement and front wheels, or to allow a front loader having an increased width to be attached to the vehicle, the mounting range must be transversely enlarged forwardly of the vehicle.
A structure taking this aspect into account is disclosed in Japanese Patent application No. 1988-333672 filed Dec. 28, 1988 (laid open under No. 1990-177803) owned by Applicant. According to this structure, long sub-frames are fixed to right and left sides of a vehicle frame assembly. Support frames and a reinforcing frame in a triangular shape in plan view extend laterally outwardly from longitudinally intermediate positions of the sub-frames. The support frames carry brackets fixed to outer ends thereof for connection to support frames of a working implement.
This structure receives and supports the load of the working implement rigidly with a long span longitudinally of the vehicle. However, its structure for connecting and supporting the working implement has the drawback of being complicated and having a large number of components.